Section 3 • Installation
Intake Velocity
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Figure
The equation used to calculate the leg height in Figure
Leg Height = (Total Airflow/Intake velocity)/Intake Perimeter
Leg Height = (247,000CFM/500FPM)/82ft
Leg Height = 6ft
In this particular case the calculated minimum height is 6 feet to maintain an intake velocity of 500FPM or less based on having the coolers place 1 fan diameter away from the nearest obstruction. Let’s look at an instal- lation where the coolers need to be placed next to the building as in Figure
Based on the information above, we are going to solve for the leg height that will provide an intake velocity of 500FPM. We know the following:
•The total airflow of the installation is 247,000CFM
•We have an intake perimeter of 3 sides 16ft, 16ft, and 25ft which totals 57’
•Our intake velocity guideline is 500FPM
The equation used to calculate the leg height in Figure
Leg Height = (Total Airflow/Intake velocity)/Intake Perimeter
Leg Height = (247,000CFM/500FPM)/57ft
Leg Height = 8.667ft
We would round the leg height up to 9ft for this particu- lar situation.
NOT PREFERRED
TOTAL INTAKE PERIMETER = 57 FEET
Figure
VSG/VSSG • Installation, Operation and Maintenance Manual •Vilter/Emerson • 35391SSG | 3 – 13 |